System and method for data prediction

ABSTRACT

A method, computer program product, and computing system for monitoring data requests made by an application being executed on a host to generate a prediction concerning a quantity of data that may be needed by the application in the future. The quantity of data is stored within a backend cache system included within a data array coupled to the host. The quantity of data is provided to the host.

TECHNICAL FIELD

This disclosure relates to cache systems and, more particularly, tosystems and methods for cache management.

BACKGROUND

Storing and safeguarding electronic content is of paramount importancein modern business. Accordingly, various systems may be employed toprotect such electronic content.

The use of solid-state storage devices is increasing in popularity. Asolid state storage device is a content storage device that usessolid-state memory to store persistent content. A solid-state storagedevice may emulate (and therefore replace) a conventional hard diskdrive. Additionally/alternatively, a solid state storage device may beused within a cache memory system. With no moving parts, a solid-statestorage device largely eliminates (or greatly reduces) seek time,latency and other electromechanical delays and failures associated witha conventional hard disk drive.

SUMMARY OF DISCLOSURE

In a first implementation, a computer-implemented method includesmonitoring data requests made by an application being executed on a hostto generate a prediction concerning a quantity of data that may beneeded by the application in the future. The quantity of data is storedwithin a backend cache system included within a data array coupled tothe host. The quantity of data is provided to the host.

One or more of the following features may be included. The quantity ofdata may be stored within a frontend cache system included within thehost. The front end cache system may be a flash-based front end cachesystem. The data array may include a plurality of electro-mechanicalstorage devices. The quantity of data may be retrieved from theplurality of electro-mechanical storage devices. The backend cachesystem may be a flash-based backend cache system. The host may beconfigured as an application server.

In another implementation, a computer program product resides on acomputer readable medium that has a plurality of instructions stored onit. When executed by a processor, the instructions cause the processorto perform operations including monitoring data requests made by anapplication being executed on a host to generate a prediction concerninga quantity of data that may be needed by the application in the future.The quantity of data is stored within a backend cache system includedwithin a data array coupled to the host. The quantity of data isprovided to the host.

One or more of the following features may be included. The quantity ofdata may be stored within a frontend cache system included within thehost. The front end cache system may be a flash-based front end cachesystem. The data array may include a plurality of electro-mechanicalstorage devices. The quantity of data may be retrieved from theplurality of electro-mechanical storage devices. The backend cachesystem may be a flash-based backend cache system. The host may beconfigured as an application server.

In another implementation, a computing system includes at least oneprocessor and at least one memory architecture coupled with the at leastone processor, wherein the computing system is configured to performoperations including monitoring data requests made by an applicationbeing executed on a host to generate a prediction concerning a quantityof data that may be needed by the application in the future. Thequantity of data is stored within a backend cache system included withina data array coupled to the host. The quantity of data is provided tothe host.

One or more of the following features may be included. The quantity ofdata may be stored within a frontend cache system included within thehost. The front end cache system may be a flash-based front end cachesystem. The data array may include a plurality of electro-mechanicalstorage devices. The quantity of data may be retrieved from theplurality of electro-mechanical storage devices. The backend cachesystem may be a flash-based backend cache system. The host may beconfigured as an application server.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features andadvantages will become apparent from the description, the drawings, andthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a storage system and a cache managementprocess coupled to a distributed computing network;

FIG. 2 is a diagrammatic view of the storage system of FIG. 1;

FIG. 3 is a flow chart of one implementation of the cache managementprocess of FIG. 1;

FIG. 4 is a flow chart of another implementation of the cache managementprocess of FIG. 1; and

FIG. 5 is a flow chart of another implementation of the cache managementprocess of FIG. 1.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

System Overview:

Referring to FIG. 1, there is shown cache management process 10 that mayreside on and may be executed by storage system 12, which may beconnected to network 14 (e.g., the Internet or a local area network).Examples of storage system 12 may include, but are not limited to: aNetwork Attached Storage (NAS) system, a Storage Area Network (SAN), apersonal computer with a memory system, a server computer with a memorysystem, and a cloud-based device with a memory system.

As is known in the art, a SAN may include one or more of a personalcomputer, a server computer, a series of server computers, a minicomputer, a mainframe computer, a RAID device and a NAS system. Thevarious components of storage system 12 may execute one or moreoperating systems, examples of which may include but are not limited to:Microsoft Windows XP Server™; Novell Netware™; Redhat Linux™, Unix, or acustom operating system, for example.

The instruction sets and subroutines of cache management process 10,which may be stored on storage device 16 included within storage system12, may be executed by one or more processors (not shown) and one ormore memory architectures (not shown) included within storage system 12.Storage device 16 may include but is not limited to: a hard disk drive;a tape drive; an optical drive; a RAID device; a random access memory(RAM); a read-only memory (ROM); and all forms of flash memory storagedevices.

Network 14 may be connected to one or more secondary networks (e.g.,network 18), examples of which may include but are not limited to: alocal area network; a wide area network; or an intranet, for example.

Various IO requests (e.g. IO request 20) may be sent from clientapplications 22, 24, 26, 28 to storage system 12. Examples of IO request20 may include but are not limited to data write requests (i.e. arequest that content be written to storage system 12) and data readrequests (i.e. a request that content be read from storage system 12).

The instruction sets and subroutines of client applications 22, 24, 26,28, which may be stored on storage devices 30, 32, 34, 36 (respectively)coupled to client electronic devices 38, 40, 42, 44 (respectively), maybe executed by one or more processors (not shown) and one or more memoryarchitectures (not shown) incorporated into client electronic devices38, 40, 42, 44 (respectively). Storage devices 30, 32, 34, 36 mayinclude but are not limited to: hard disk drives; tape drives; opticaldrives; RAID devices; random access memories (RAM); read-only memories(ROM), and all forms of flash memory storage devices. Examples of clientelectronic devices 38, 40, 42, 44 may include, but are not limited to,personal computer 38, laptop computer 40, personal digital assistant 42,notebook computer 44, a server (not shown), a data-enabled, cellulartelephone (not shown), and a dedicated network device (not shown).

Users 46, 48, 50, 52 may access storage system 12 directly throughnetwork 14 or through secondary network 18. Further, storage system 12may be connected to network 14 through secondary network 18, asillustrated with link line 54.

The various client electronic devices may be directly or indirectlycoupled to network 14 (or network 18). For example, personal computer 38is shown directly coupled to network 14 via a hardwired networkconnection. Further, notebook computer 44 is shown directly coupled tonetwork 18 via a hardwired network connection. Laptop computer 40 isshown wirelessly coupled to network 14 via wireless communicationchannel 56 established between laptop computer 40 and wireless accesspoint (i.e., WAP) 58, which is shown directly coupled to network 14. WAP58 may be, for example, an IEEE 802.11a, 802.11b, 802.11g, 802.11n,Wi-Fi, and/or Bluetooth device that is capable of establishing wirelesscommunication channel 56 between laptop computer 40 and WAP 58. Personaldigital assistant 42 is shown wirelessly coupled to network 14 viawireless communication channel 60 established between personal digitalassistant 42 and cellular network/bridge 62, which is shown directlycoupled to network 14.

Client electronic devices 38, 40, 42, 44 may each execute an operatingsystem, examples of which may include but are not limited to MicrosoftWindows™, Microsoft Windows CE™, Redhat Linux™, or a custom operatingsystem.

For illustrative purposes, storage system 12 will be described as beinga network-based storage system that includes a plurality ofelectro-mechanical backend storage devices. However, this is forillustrative purposes only and is not intended to be a limitation ofthis disclosure, as other configurations are possible and are consideredto be within the scope of this disclosure. For example and as discussedabove, storage system 12 may be a personal computer that includes asingle electro-mechanical storage device.

Referring also to FIG. 2, storage system 12 may include a servercomputer/controller (e.g. server computer/controller 100) and aplurality of storage targets T_(1-n) (e.g. storage targets 102, 104,106, 108). Storage targets 102, 104, 106, 108 may be configured toprovide various levels of performance and/or high availability. Forexample, one or more of storage targets 102, 104, 106, 108 may beconfigured as a RAID 0 array, in which data is striped across storagetargets. By striping data across a plurality of storage targets,improved performance may be realized. However, RAID 0 arrays do notprovide a level of high availability. Accordingly, one or more ofstorage targets 102, 104, 106, 108 may be configured as a RAID 1 array,in which data is mirrored between storage targets. By mirroring databetween storage targets, a level of high availability is achieved asmultiple copies of the data are stored within storage system 12.

While storage targets 102, 104, 106, 108 are discussed above as beingconfigured in a RAID 0 or RAID 1 array, this is for illustrativepurposes only and is not intended to be a limitation of this disclosure,as other configurations are possible. For example, storage targets 102,104, 106, 108 may be configured as a RAID 3, RAID 4, RAID 5 or RAID 6array.

While in this particular example, storage system 12 is shown to includefour storage targets (e.g. storage targets 102, 104, 106, 108), this isfor illustrative purposes only and is not intended to be a limitation ofthis disclosure. Specifically, the actual number of storage targets maybe increased or decreased depending upon e.g. the level ofredundancy/performance/capacity required.

Storage system 12 may also include one or more coded targets 110. As isknown in the art, a coded target may be used to store coded data thatmay allow for the regeneration of data lost/corrupted on one or more ofstorage targets 102, 104, 106, 108. An example of such a coded targetmay include but is not limited to a hard disk drive that is used tostore parity data within a RAID array.

While in this particular example, storage system 12 is shown to includeone coded target (e.g., coded target 110), this is for illustrativepurposes only and is not intended to be a limitation of this disclosure.Specifically, the actual number of coded targets may be increased ordecreased depending upon e.g. the level ofredundancy/performance/capacity required.

Examples of storage targets 102, 104, 106, 108 and coded target 110 mayinclude one or more electro-mechanical hard disk drives, wherein acombination of storage targets 102, 104, 106, 108 and coded target 110may form non-volatile, electro-mechanical memory system 112.

The manner in which storage system 12 is implemented may vary dependingupon e.g. the level of redundancy/performance/capacity required. Forexample, storage system 12 may be a RAID device in which servercomputer/controller 100 is a RAID controller card and storage targets102, 104, 106, 108 and/or coded target 110 are individual“hot-swappable” hard disk drives. An example of such a RAID device mayinclude but is not limited to an NAS device. Alternatively, storagesystem 12 may be configured as a SAN, in which servercomputer/controller 100 may be e.g., a server computer and each ofstorage targets 102, 104, 106, 108 and/or coded target 110 may be a RAIDdevice and/or computer-based hard disk drive. Further still, one or moreof storage targets 102, 104, 106, 108 and/or coded target 110 may be aSAN.

In the event that storage system 12 is configured as a SAN, the variouscomponents of storage system 12 (e.g. server computer/controller 100,storage targets 102, 104, 106, 108, and coded target 110) may be coupledusing network infrastructure 114, examples of which may include but arenot limited to an Ethernet (e.g., Layer 2 or Layer 3) network, a fiberchannel network, an InfiniBand network, or any other circuitswitched/packet switched network.

Storage system 12 may execute all or a portion of cache managementprocess 10. The instruction sets and subroutines of cache managementprocess 10, which may be stored on a storage device (e.g., storagedevice 16) coupled to server computer/controller 100, may be executed byone or more processors (not shown) and one or more memory architectures(not shown) included within server computer/controller 100. Storagedevice 16 may include but is not limited to: a hard disk drive; a tapedrive; an optical drive; a RAID device; a random access memory (RAM); aread-only memory (ROM); and all forms of flash memory storage devices.

As discussed above, various IO requests (e.g. IO request 20) may begenerated. For example, these IO requests may be sent from clientapplications 22, 24, 26, 28 to storage system 12.Additionally/alternatively and when server computer/controller 100 isconfigured as an application server, these IO requests may be internallygenerated within server computer/controller 100. Examples of IO request20 may include but are not limited to data write request 116 (i.e. arequest that content 118 be written to storage system 12) and data readrequest 120 (i.e. a request that content 118 be read from storage system12).

Server computer/controller 100 may include input-output logic 122 (e.g.,a network interface card or a Host Bus Adaptor (HBA)), processing logic124, and first cache system 126. Examples of first cache system 126 mayinclude but are not limited to a volatile, solid-state, cache memorysystem (e.g., a dynamic RAM cache memory system) and/or a non-volatile,solid-state, cache memory system (e.g., a flash-based, cache memorysystem).

During operation of server computer/controller 100, content 118 to bewritten to storage system 12 may be received by input-output logic 122(e.g. from network 14 and/or network 18) and processed by processinglogic 124. Additionally/alternatively and when servercomputer/controller 100 is configured as an application server, content118 to be written to storage system 12 may be internally generated byserver computer/controller 100. As will be discussed below in greaterdetail, processing logic 124 may initially store content 118 withinfirst cache system 126.

Depending on the manner in which first cache system 126 is configured,processing logic 124 may immediately write content 118 to second cachesystem 128/non-volatile, electro-mechanical memory system 112 (if firstcache system 126 is configured as a write-through cache) or maysubsequently write content 118 to second cache system 128/non-volatile,electro-mechanical memory system 112 (if first cache system 126 isconfigured as a write-back cache). Additionally and in certainconfigurations, processing logic 124 may calculate and store coded dataon coded target 110 (included within non-volatile, electromechanicalmemory system 112) that may allow for the regeneration of datalost/corrupted on one or more of storage targets 102, 104, 106, 108. Forexample, if processing logic 124 was included within a RAID controllercard or an NAS/SAN controller, processing logic 124 may calculate andstore coded data on coded target 110. However, if processing logic 124was included within e.g., an applications server, data array 130 maycalculate and store coded data on coded target 110.

Examples of second cache system 128 may include but are not limited to avolatile, solid-state, cache memory system (e.g., a dynamic RAM cachememory system) and/or a non-volatile, solid-state, cache memory system(e.g., a flash-based, cache memory system).

The combination of second cache system 128 and non-volatile,electromechanical memory system 112 may form data array 130, whereinfirst cache system 126 may be sized so that the number of times thatdata array 130 is accessed may be reduced. Accordingly, by sizing firstcache system 126 so that first cache system 126 retains a quantity ofdata sufficient to satisfy a significant quantity of IO requests (e.g.,IO request 20), the overall performance of storage system 12 may beenhanced.

Further, second cache system 128 within data array 130 may be sized sothat the number of times that non-volatile, electromechanical memorysystem 112 is accessed may be reduced. Accordingly, by sizing secondcache system 128 so that second cache system 128 retains a quantity ofdata sufficient to satisfy a significant quantity of IO requests (e.g.,IO request 20), the overall performance of storage system 12 may beenhanced.

As discussed above, the instruction sets and subroutines of cachemanagement process 10, which may be stored on storage device 16 includedwithin storage system 12, may be executed by one or more processors (notshown) and one or more memory architectures (not shown) included withinstorage system 12. Accordingly, in addition to being executed on servercomputer/controller 100, some or all of the instruction sets andsubroutines of cache management process 10 may be executed by one ormore processors (not shown) and one or more memory architectures (notshown) included within data array 130.

The Cache Management Process:

As discussed above, server computer/controller 100 may include firstcache system 126, wherein processing logic 124 may initially storecontent 118 within first cache system 126. Depending on the manner inwhich first cache system 126 is configured, processing logic 124 mayimmediately write content 118 included in a write request to data array130 (if first cache system 126 is configured as a write-through cache)or may subsequently write content 118 included in a write request todata array 130 (if first cache system 126 is configured as a write-backcache). Further, content (e.g., content 118) retrieved from data array130 in response to a read request may be written to first cache system126. For illustrative purposes, assume that first cache system 126 isconfigured as a write-through cache.

First cache system 126 may be compartmentalized into a plurality ofportions that each may be configured to perform a different task. Forexample, first cache system 126 may include local IO portion 132 thatmay be configured to temporarily store content 118 in the mannerdescribed above (e.g., in response to write requests providing content118 to server computer/controller 100 and/or in response to readrequests asking for content 118 from server computer/controller 100).First cache system 126 may further include local drive portion 134.Local drive portion 134 may be configured as usable storage space by oneor more applications being executed on server computer/controller 100.For example, if server computer/controller 100 is executing a databaseapplication and that database application uses a swap file, that swapfile may be stored within local drive portion 134 of first cache system126. First cache system 126 may additionally include data array cacheportion 136 and data array failover portion 138, the functionality ofwhich will be discussed below in greater detail.

As discussed above, server computer/controller 100 may be configured asan application server. Accordingly, server computer/controller 100 mayexecute one or more applications (e.g., application 140). An example ofapplication 140 may include a database application (such as Oracle™),wherein the various associated database files (e.g., database recordfiles, temporary files, index files, and log files) may be stored ondata array 130.

Referring also to FIG. 3, cache management process 10 may monitor 200data requests made by an application (e.g. application 140) beingexecuted on a host (e.g., server computer/controller 100) to generate aprediction (e.g., prediction 142) concerning a quantity of data that maybe needed/requested by application 140 in the future. For example, cachemanagement process 10 may monitor 200 the way that application 140 isperforming to predict the quantity of data that application 140 mayneed/request in the near future so that it may be prefetched inanticipation of being needed/requested. Accordingly, assume that cachemanagement process 10 notices that application 140 is sequentiallyverifying database records that are stored on data array 130. Further,assume that cache management process 10 notices that these databaserecords are being retrieved from data array 130 one-thousand records ata time, and that the last batch of database records included databaserecords 9,000-9,999. Accordingly, cache management process 10 maypredict that the quantity of data that application 140 may next requestis database records 10,000-10,999 (e.g., predicted data 144).

Accordingly, cache management process 10 may store 202 predicted data144 (e.g., database records 10,000-10,999) within a backend cache system(e.g., second cache system 128) included within data array 130 coupledto the host (e.g., server computer/controller 100). As discussed above,data array 130 may include a plurality of electro-mechanical storagedevices (e.g., non-volatile, electro-mechanical memory system 112).Accordingly, cache management process 10 may first retrieve 204predicted data 144 (e.g., database records 10,000-10,999) from theplurality of electro-mechanical storage devices (e.g., non-volatile,electro-mechanical memory system 112) and then store 202 the same withinsecond cache system 128.

To further enhance the performance of the host (e.g., servercomputer/controller 100), cache management process 10 may provide 206predicted data 144 (e.g., database records 10,000-10,999) to the host(e.g., server computer/controller 100), which may be stored 208 within afrontend cache system (e.g., first cache system 126) included within thehost (e.g., server computer/controller 100). Accordingly, in the eventthat prediction 142 proves to be accurate and application 140 doesindeed need/request predicted data 144 (e.g., database records10,000-10,999), such data will already be present within first cachesystem 126 and will not need to be obtained from data array 130.

As discussed above, examples of storage targets 102, 104, 106, 108 andcoded target 110 may include one or more electro-mechanical hard diskdrives, wherein a combination of storage targets 102, 104, 106, 108 andcoded target 110 may form non-volatile, electro-mechanical memory system112. Unfortunately, such electro-mechanical hard disk drives may sufferelectrical, mechanical, or electro-mechanical failures.

Fortunately and as discussed above, processing logic 124 may calculateand store coded data on coded target 110 (included within non-volatile,electromechanical memory system 112) that may allow for the regenerationof data lost/corrupted on one or more of storage targets 102, 104, 106,108 (e.g. due to the failure of an electro-mechanical hard disk drive).

Unfortunately, in the event of such a hard disk drive failure, theregeneration of data that is lost/corrupted is a computationallyexpensive task that may take multiple days to complete. Accordingly, inthe event that a hard disk drive is failing, it is desirable to back upthe data included within the failing hard disk drive prior to suchfailure.

Accordingly and referring also to FIG. 4, cache management process 10may be configured to receive 250 an indication (e.g. indication 146)that a hard disk drive (e.g. storage target 106) within a data array(e.g. data array 130) is failing, thus defining a failing hard diskdrive. Specifically, the failing hard disk drive (e.g. storage target106) may be configured to provide some form of indication that the sameis failing. Additionally/alternatively, cache management process 10 maybe configured to monitor the performance of the various hard disk drivesincluded within disk array 130 to identify hard disk drives that appearto be failing.

As discussed above, first cache system 126 may include local IO portion132, local drive portion 134, data array cache portion 136, and dataarray failover portion 138. Data array failover portion 138 may becreated only upon indication 146 being received 250 by cache managementprocess 10. Accordingly and absent such an indication, data arrayfailover portion 138 may not exist and the area of first cache system126 that would have been utilized by data array failover portion 138 maybe utilized by one of the other above-described portions (e.g. local IOportion 132, local drive portion 134) of first cache system 126.

Accordingly and upon receiving 250 indication 146 that storage target106 is failing, cache management process 10 may define 252 a failoverportion (e.g. data array failover portion 138) of the front end cachesystem (e.g. first cache system 126) in response to receiving indication146 that the hard disk drive (e.g. storage target 106) within data array130 is failing. When defining 252 data array failover portion 138, cachemanagement process 10 may flush 254 any cache data that was currentlyresiding within data array failover portion 138 of first cache system126. Specifically, the failure of a hard disk drive within data array130 (and the potential for data loss) is of paramount importance.Accordingly, when cache management process 10 requests a portion offirst cache system 126 for use as data array failover portion 138 inresponse to receiving 250 indication 146 that e.g. storage target 106within data array 130 is failing, such a request may take precedent overe.g. using such space within first cache system 126 for data cachingpurposes. Further, since first cache system 126 is configured as awrite-through cache, any data received by first cache system 126 inresponse to a write request is immediately written to data array 130.Accordingly, flushing 254 cache data that is currently residing withinthe portion of first cache system 126 that will be used for data arrayfailover portion 138 should not result in any data loss.

Once data array failover portion 138 is defined, cache managementprocess 10 may copy 256 at least a portion of the data included withinthe failing hard disk drive (e.g. storage target 106) to data arrayfailover portion 138 of first cache system 126 included within the host(e.g., server computer/controller 100) coupled to data array 130, thusdefining backup data set 148.

The data included within the failing hard disk drive (e.g. storagetarget 106) may vary depending upon the manner in which data array 130is configured. For example, the entirety of storage target 106 may beconfigured as a single LUN (logical unit number), which is essentially alogical drive that is accessible by one or more applications running one.g., server computer/controller 100. Alternatively, only a portion ofstorage target 106 may be configured as a single LUN, wherein otherportions of storage target 106 are configured as other LUNs. Furtherstill, the entirety of storage target 106 may be configured as a portionof a single LUN, wherein other storage targets are utilized to defineother portions of that LUN. Accordingly, when copying 256 at least aportion of the data included within storage target 106 to data arrayfailover portion 138, one or more complete or partial LUNs may be copiedto data array failover portion 130.

Assume for illustrative purposes that the failing hard disk drive (e.g.storage target 106) is subsequently replaced with a “healthy” hard diskdrive. Accordingly, the “healthy” hard disk drive may be configured toprovide a signal indicating that storage target 106 is no longerfailing. Alternatively, cache management system 10 may be configured tomonitor storage target 106 for any indications of failure and, upon nolonger receiving such indications, may deem storage target 106“healthy”.

Accordingly, upon cache management process 10 receiving 258 anindication (not shown) that the failing hard disk drive (e.g. storagetarget 106) has been replaced (thus defining a replacement hard diskdrive), cache management process 10 may restore 260 at least a portionof backup data set 148 onto the replacement hard disk drive (e.g. the“healthy” hard disk drive that replaced failing storage target 106).

Accordingly, by restoring 260 at least a portion of backup dataset 148onto the replacement hard disk drive, the computationally-expensiveprocess of regenerating data that was stored on failing storage target106 may be avoided.

As discussed above, second cache system 128 within data array 130 may besized so that the number of times that non-volatile, electromechanicalmemory system 112 is accessed may be reduced. Accordingly, by sizingsecond cache system 128 so that second cache system 128 retains aquantity of data sufficient to satisfy a significant quantity of IOrequests (e.g., IO request 20), the overall performance of storagesystem 12 may be enhanced. Unfortunately, even the largest cache systemwill eventually fill up with cached data and cold data (e.g. data withinthe cache system that was not accessed for a considerable amount oftime) may need to be overwritten.

As discussed above, second cache system 128 is the cache system for allof data array 130. Since data array 130 may be accessed by many hosts(e.g., server computer/controller 100), second cache system 128 maybecome filled with cached data quite quickly. Accordingly, second cachesystem 128 may be configured in a least-recently-used fashion, so thatdata that has grown cold (has not been accessed for a considerableamount of time) may be flushed from second cache system 128.

For example, second cache system 128 may be divided into a plurality ofcache slots. An example of such a cache slot may be a 64 kb portion ofsecond cache system 128. Accordingly and in such an implementation, eachgigabyte of second cache system 128 may be divided in 16,384 64 kb cacheslots. Each of these cache slots may be utilized to cache data for asingle host (e.g., 64 kb of data cached for a single host), for aplurality of hosts (e.g., 16 kb of data cached for each of four hosts),or a plurality of cache slots may be utilized to cache data for one host(e.g., four 64 kb slots cache 256 kb of data for a single host).

As second cache system 128 has a finite size and, therefore, a finitenumber of cache slots, the more that second cache system 128 is used,the faster the cache slots within second cache system 128 may be filledand, therefore, the quicker the data within a slot may be deemed to havegrown cold. Accordingly, once all of the cache slots within second cachesystem 128 are filled with cached data, the cache slot that contains thecoldest cached data (e.g., the cached data that hasn't been used in thelongest period of time) will be overwritten with new “hot” data to becached.

Referring also to FIG. 5, instead of simply overwriting the coldestcached data, cache management process 10 may be configured to store thiscold cached data within a portion of first cache system 126.Specifically, cache management process 10 may define 300 a portion of afrontend cache system (e.g., first cache system 126) for use as dataarray cache portion 136. Data array cache portion 136 may be configuredto stored such cold cached data before the data is overwritten with newdata to be cached.

For example, cache management process 10 may identify 302 one or morecache slots included within a backend cache system (e.g., second cachesystem 128) that are going to be overwritten with hot cache data and arecurrently filled with cold cache data. Assume that second cache system128 is filled and 640 kb of hot cache data just came in that needs to bestored within second cache system 128. Accordingly and in theimplementation in which a cache slot is 64 kb in size, the ten cacheslots (e.g., cache slots 150) that contain the coldest cached data willbe identified 302 by cache management process 10.

Cache management process 10 may copy the coldest cached data (e.g., colddata 152) and write 304 cold data 152 included within cache slots 150 ofthe backend cache system (e.g., second cache system 128) to e.g., tencache slots 154 included within data array cache portion 136.

Once cold data 152 is written to cache slots 154 of data array cacheportion 136, cache management process 10 may write 306 hot cache data(e.g., hot data 156) to cache slots 150 included within the backendcache system (e.g., second cache system 128).

In a fashion similar to second cache system 128, the front end cachesystem (e.g., first cache system 126) may be configured in aleast-recently-used fashion, so that data that has grown cold (has notbeen accessed in a considerable amount of time) may be flushed fromfirst cache system 126.

General:

As will be appreciated by skilled in the art, the present disclosure maybe embodied as a method, a system, or a computer program product.Accordingly, the present disclosure may take the form of an entirelyhardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore,the present disclosure may take the form of a computer program producton a computer-usable storage medium having computer-usable program codeembodied in the medium.

Any suitable computer usable or computer readable medium may beutilized. The computer-usable or computer-readable medium may be, forexample but not limited to, an electronic, magnetic, optical,electromagnetic, infrared, or semiconductor system, apparatus, device,or propagation medium. More specific examples (a non-exhaustive list) ofthe computer-readable medium may include the following: an electricalconnection having one or more wires, a portable computer diskette, ahard disk, a random access memory (RAM), a read-only memory (ROM), anerasable programmable read-only memory (EPROM or Flash memory), anoptical fiber, a portable compact disc read-only memory (CD-ROM), anoptical storage device, a transmission media such as those supportingthe Internet or an intranet, or a magnetic storage device. Thecomputer-usable or computer-readable medium may also be paper or anothersuitable medium upon which the program is printed, as the program can beelectronically captured, via, for instance, optical scanning of thepaper or other medium, then compiled, interpreted, or otherwiseprocessed in a suitable manner, if necessary, and then stored in acomputer memory. In the context of this document, a computer-usable orcomputer-readable medium may be any medium that can contain, store,communicate, propagate, or transport the program for use by or inconnection with the instruction execution system, apparatus, or device.The computer-usable medium may include a propagated data signal with thecomputer-usable program code embodied therewith, either in baseband oras part of a carrier wave. The computer usable program code may betransmitted using any appropriate medium, including but not limited tothe Internet, wireline, optical fiber cable, RF, etc.

Computer program code for carrying out operations of the presentdisclosure may be written in an object oriented programming languagesuch as Java, Smalltalk, C++ or the like. However, the computer programcode for carrying out operations of the present disclosure may also bewritten in conventional procedural programming languages, such as the“C” programming language or similar programming languages. The programcode may execute entirely on the user's computer, partly on the user'scomputer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through a local area network/a widearea network/the Internet (e.g., network 14).

The present disclosure is described with reference to flowchartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products according to embodiments of the disclosure. Itwill be understood that each block of the flowchart illustrations and/orblock diagrams, and combinations of blocks in the flowchartillustrations and/or block diagrams, may be implemented by computerprogram instructions. These computer program instructions may beprovided to a processor of a general purpose computer/special purposecomputer/other programmable data processing apparatus, such that theinstructions, which execute via the processor of the computer or otherprogrammable data processing apparatus, create means for implementingthe functions/acts specified in the flowchart and/or block diagram blockor blocks.

These computer program instructions may also be stored in acomputer-readable memory that may direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instruction meanswhich implement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer or other programmableapparatus to produce a computer implemented process such that theinstructions which execute on the computer or other programmableapparatus provide steps for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

The flowcharts and block diagrams in the figures may illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present disclosure. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustrations,and combinations of blocks in the block diagrams and/or flowchartillustrations, may be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present disclosure has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the disclosure in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the disclosure. Theembodiment was chosen and described in order to best explain theprinciples of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various embodiments with various modifications as are suited to theparticular use contemplated.

A number of implementations have been described. Having thus describedthe disclosure of the present application in detail and by reference toembodiments thereof, it will be apparent that modifications andvariations are possible without departing from the scope of thedisclosure defined in the appended claims.

What is claimed is:
 1. A computer-implemented method comprising:monitoring data requests made by an application being executed on a hostto generate a prediction concerning a quantity of data that may beneeded by the application in the future including monitoring performanceof the application on the host to generate the prediction, wherein thehost is configured as an application server including a first cachesystem having a local cache portion, a local drive portion, a data arraycache portion and a data array failover portion; storing the quantity ofdata within a backend cache system included within a data array coupledto the host; and providing the quantity of data to the host.
 2. Thecomputer-implemented method of claim 1 further comprising: storing thequantity of data within a frontend cache system included within thehost.
 3. The computer-implemented method of claim 2 wherein the frontend cache system is a flash-based front end cache system.
 4. Thecomputer-implemented method of claim 1 wherein the data array includes aplurality of electro-mechanical storage devices.
 5. Thecomputer-implemented method of claim 4 further comprising: retrievingthe quantity of data from the plurality of electro-mechanical storagedevices.
 6. The computer-implemented method of claim 1 wherein thebackend cache system is a flash-based backend cache system.
 7. Acomputer program product residing on a non-transitory computer readablemedium having a plurality of instructions stored thereon which, whenexecuted by a processor, cause the processor to perform operationscomprising: monitoring data requests made by an application beingexecuted on a host to generate a prediction concerning a quantity ofdata that may be needed by the application in the future includingmonitoring performance of the application on the host to generate theprediction, wherein the host is configured as an application serverincluding a first cache system having a local cache portion, a localdrive portion, a data array cache portion and a data array failoverportion; storing the quantity of data within a backend cache systemincluded within a data array coupled to the host; and providing thequantity of data to the host.
 8. The computer program product of claim 7further comprising instructions for: storing the quantity of data withina frontend cache system included within the host.
 9. The computerprogram product of claim 8 wherein the front end cache system is aflash-based front end cache system.
 10. The computer program product ofclaim 7 wherein the data array includes a plurality ofelectro-mechanical storage devices.
 11. The computer program product ofclaim 10 further comprising instructions for: retrieving the quantity ofdata from the plurality of electro-mechanical storage devices.
 12. Thecomputer program product of claim 7 wherein the backend cache system isa flash-based backend cache system.
 13. A computing system including atleast one processor and at least one memory architecture coupled withthe at least one processor, wherein the computing system is configuredto perform operations comprising: monitoring data requests made by anapplication being executed on a host to generate a prediction concerninga quantity of data that may be needed by the application in the futureincluding monitoring performance of the application on the host togenerate the prediction, wherein the host is configured as anapplication server including a first cache system having a local cacheportion, a local drive portion, a data array cache portion and a dataarray failover portion; storing the quantity of data within a backendcache system included within a data array coupled to the host; andproviding the quantity of data to the host.
 14. The computing system ofclaim 13 further configured to perform operations comprising: storingthe quantity of data within a frontend cache system included within thehost.
 15. The computing system of claim 14 wherein the front end cachesystem is a flash-based front end cache system.
 16. The computing systemof claim 13 wherein the data array includes a plurality ofelectro-mechanical storage devices.
 17. The computing system of claim 16further configured to perform operations comprising: retrieving thequantity of data from the plurality of electro-mechanical storagedevices.
 18. The computing system of claim 15 wherein the backend cachesystem is a flash-based backend cache system.